Our overall goal is to develop a method for controlling a multiple joint artificial arm using the small electrical signals (EMG) which are generated by an amputee's remnant musculature. The method is implemented via a set of controller equations which are rigorously derived based on a fundamental postulate that blends a number of areas in biomechanics with Newtonian dynamics expressed through spacial multi-axis linkage equations (theoretical details are contained in the original proposal and the previous progress report). Specifically, we are attempting to demonstrate on amputees, that a four degree of freedom artificial limb with humeral rotation, elbow flexion, wrist rotation and hand closure can be simultaneously and smoothly controlled using the EMG signals from approximately seven shoulder and stump muscles. The secondary goal of our project is to contribute fundamental knowledge in the area of biomechanics. We have assembled an extensive experimental facility for examining the human, neuromusculoskeletal system and we are developing a substantial data base on shoulder/elbow torques as a function of cutaneously measured EMG signals, limb position and velocity. The data base, when used with the analytically rigorous control equations, greatly facilitates interpretation and representation of limb performance. Progress is being achieved in the quantification of knowledge in the following areas: (1) musculoskeletal anatomy, (2) the relationship between muscularly generated torques about joints and cutaneously measured EMG signals, (3) patterns of coordination of multiple redundant muscles of the arm and shoulder, and (4) methods for processing EMG signals to permit better estimation of muscular force.